A Massive, Undulating Foam Blob Has Taken Over a Street in California

A street in Santa Clara, California, was swallowed by a giant foam blob over the weekend, reaching up to 1 metre (3.5 feet) high, and filling the equivalent of a city block.

The foam turned out to be the result of a fire system malfunctioning in a nearby airport hangar, which caused a deluge of flame-retarding foam to spill out of the airport and into the neighbouring Martin Avenue, in what seemed to be an unstoppable flood.

Local news station KTVU Fox 2 covered the growth of the foam tide on Facebook live, back when authorities had no clue what was causing it. The footage quickly went viral (note, there's some white noise at the start before the broadcast starts):

Local fire captain Mitch Matlow told KTVU that despite his years of work with the San Jose Fire Department, he's never seen anything like this before.

The MVP of the day goes to this guy, who looks like he's having the time of his life riding through the mysterious foam, before anyone knew where it was coming from:

Unfortunately, Matlow explained that the flame-retarding foam is a carcinogen in high concentrations, and can cause skin irritation when diluted.

He's since spoken to the bike rider, who was apparently unconcerned, so let's hope this guy hasn't suffered any side effects.

Matlow is advising anyone who came in contact with the foam to rinse it off with water and seek medical attention. No injuries have been reported so far.

The foam leak started on Saturday morning around 11am, after a fire alarm in a hangar on Mineta San Jose International Airport accidentally went off.

Fire officials immediately arrived on the scene only to find a 3-metre (10-foot) wall of foam, and no sign of flames.

The foam is an aqueous film forming foam (AFFF), which works by cooling a fire down and coating the fuel, preventing it from coming into contact with any more oxygen, and stopping further combustion.

The foam was first invented by Russian engineer Aleksandr Loran back in 1902, and it's the same kind of foam you'd find in a standard fire extinguisher.

Except that there are now several types of AFFF tailored to work best in their specific environment. The kind used in hangars are high-expansion foams that expand more than 200 to 1,000 times their condensed volume to quickly fill a highly flammable space, which is why the foam blob so rapidly took over Martin Avenue.

Locals and news sites also took to Twitter to share incredible images of the spill - which turned a huge section of Martin Avenue into a giant foam pit.

Firefighting foam released from back of @FlySJC hangar is blowing around in the wind. It looks like soap, but I wouldn't advise touching it. pic.twitter.com/fDI3j0gmP7

Environmental cleanup company Clean Harbors has been hired to remove the foam. They've already managed to trap the material that entered storm drains, so that it can't pose an environmental threat to local water sources.

They're now using a dissolving agent that will break down the bubbles, and will drive a giant vacuum cleaner truck in the area to suck it all up (which sounds just as awesome to watch as the undulating foam tide in the first place, tbh).

They're hoping to have it all cleaned up in the next few days, before any expected rainfall. But until then, the public is asked to avoid Martin Avenue east of Lafayette Street.